Embryology Lecture 1

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Questions and Answers

What is the result when fertilization does not occur?

The uterine tube expands

The ovary stops functioning

Fertilization occurs in the cervix

The egg degenerates, and menstruation occurs (correct)

Where does the process of fertilization occur?

In the ampullary region of the uterine tube (correct)

In the cervix

In the ovary

In the uterus

What is the purpose of capacitation?

To prevent the acrosome reaction

To condition the sperm to penetrate the corona cells (correct)

To inhibit fertilization

To facilitate fertilization

What triggers the acrosome reaction?

Binding to the zona pellucida Signup and view all the answers

What is the function of the acrosome reaction?

To facilitate the penetration of the zona pellucida Signup and view all the answers

What is the purpose of Phase I of fertilization?

To penetrate the corona radiata Signup and view all the answers

What is the function of the zona pellucida?

To facilitate and maintain sperm binding Signup and view all the answers

What happens to the permeability of the zona pellucida during fertilization?

It changes when the head of the sperm comes in contact with the oocyte surface Signup and view all the answers

What is the purpose of the acrosome reaction?

To expose the posterior region of the sperm head Signup and view all the answers

What is the result of the fusion of the sperm and oocyte membranes?

Restoration of the diploid number of chromosomes Signup and view all the answers

What happens to the cells during cleavage?

They decrease in size with each division Signup and view all the answers

What is the name of the cluster of cells that forms after four initial cell divisions?

Morula Signup and view all the answers

What is the term for the process of rapid cell divisions after fertilization?

Cleavage Signup and view all the answers

What is the term for the cells that derive from cleavage up to the blastula stage?

Blastomeres Signup and view all the answers

What is the term for all structures that develop from the zygote, both embryonic and extraembryonic?

Conceptus Signup and view all the answers

What is the branch of biology that studies the development of gametes, fertilization, and development of embryos and fetuses?

Embryology Signup and view all the answers

What is the result of the zona reaction?

Alteration of the properties of the zona pellucida Signup and view all the answers

At what stage of development is the embryo termed a fetus?

Beginning of the ninth week Signup and view all the answers

What is the duration of the normal period of gestation?

38 weeks Signup and view all the answers

What is the term for the study of congenital disorders that occur before birth?

Teratology Signup and view all the answers

During which week of development does the concept shift from a single-celled zygote into a multi-leveled, multi-dimensional fetal body plan?

Eighth week Signup and view all the answers

What is the term for the process by which the fertilized egg develops into an embryo?

Human Embryogenesis Signup and view all the answers

What is the process that occurs after fertilization, resulting in the formation of a multicellular embryo?

Mitotic cleavage Signup and view all the answers

What is the term for the stage of development during which the embryo has more recognizable external features and a more complete set of developing organs?

Fetus Signup and view all the answers

What is the term used to describe the solid sphere of cells within the zona pellucida?

Morula Signup and view all the answers

What is the primary function of the trophoblast layer?

To surround the inner cell mass and blastocoel Signup and view all the answers

What is the term used to describe the process of the blastocyst burrowing into the endometrium?

Invasion Signup and view all the answers

What is the first cavity formed during embryonic development?

Blastocoel Signup and view all the answers

When does implantation typically occur?

During the first and second week of gestation Signup and view all the answers

What is the term used to describe the stage of embryonic development where fluids penetrate the zona pellucida?

Blastulation Signup and view all the answers

What is the primary function of the corpus luteum after ovulation?

To release female sex hormones, including progesterone and estrogen Signup and view all the answers

What is the term for the cluster of cells that surround the oocyte in the ovarian follicle and after ovulation?

Cumulus oophorus Signup and view all the answers

What is the result of the LH surge in the ovulation process?

The release of the oocyte from the follicle Signup and view all the answers

What is the purpose of the fimbriae of the uterine tube?

To transport the ovum to the uterus Signup and view all the answers

What happens to the endometrium if fertilization does not occur?

It degenerates Signup and view all the answers

What is the term for the structure that forms from the ruptured follicle after ovulation?

Corpus luteum Signup and view all the answers

What is the result of the failure of the blastocyst to implant within the endometrium?

The degeneration of the endometrium Signup and view all the answers

What is the term for the layer of cells that surrounds the oocyte after ovulation?

Corona radiata Signup and view all the answers

Study Notes

Embryology

Human embryogenesis is the process by which a fertilized egg develops into an embryo, studying the development of gametes, fertilization, and development of embryos and fetuses.
Human embryology specifically studies development during the first eight weeks after fertilization.

Gamete Approximation and Fertilization

Ovulation is the process by which a mature egg is released from the ovary, triggered by a surge of luteinizing hormone (LH).
The released egg is covered by the zona pellucida and one or more layers of follicular cells.
Fertilization occurs in the ampullary region of the uterine tube, involving capacitation, the acrosome reaction, and penetration of the corona radiata and zona pellucida.

Capacitation and Acrosome Reaction

Capacitation is a period of conditioning in the female reproductive tract, allowing sperm to pass through corona cells and undergo the acrosome reaction.
The acrosome reaction, induced by zona proteins, releases enzymes needed to penetrate the zona pellucida.

Phases of Fertilization

Phase I: Capacitated sperm pass through the corona radiata.
Phase II: Sperm penetrate the zona pellucida, releasing acrosomal enzymes.
Phase III: Fusion of oocyte and sperm cell membranes occurs.

Results of Fertilization

Restoration of the diploid number of chromosomes occurs, with half from the father and half from the mother.
The sex of the new individual is determined, with an X-carrying sperm producing a female embryo and a Y-carrying sperm producing a male embryo.
Initiation of cleavage occurs, resulting in rapid cell divisions with no significant growth.

Cleavage and Morula Formation

Cleavage results in a cluster of cells called the morula, with at least four initial cell divisions producing a dense ball of at least sixteen cells.
The morula forms within four days as it travels to the uterine cavity.

Blastulation (Blastocyst Formation)

The morula develops into a blastocyst, consisting of an inner cell mass (ICM) and an outer layer of cells called the trophoblast.
The blastocoel is a fluid-filled cavity formed within the blastocyst.

Implantation

Implantation is a complex biochemical and mechanical process that begins in the first week of gestation and extends into the second week.
The process involves apposition, attachment, and invasion of the blastocyst into the uterine wall.

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Description

This quiz covers the basics of human embryology, including embryogenesis, fertilization, and development of embryos and fetuses. It also touches on congenital disorders that occur before birth.